Antihyperglycaemic and protective effects of flavonoids on streptozotocin–induced diabetic rats

The antihyperglycaemic effect of eight standard flavonoids, previously identified in the ethanol extract of the claimed antidiabetic plant Genista tenera , was evaluated on streptozotocin (STZ)‐induced diabetic Wistar rats. The aglycones apigenin, chrysoeriol and genistein, the monoglucosides apigenin 7‐ O ‐glucoside, luteolin 7‐ O ‐glucoside and genistein 7‐ O ‐glucoside and the diglycosides rutin and luteolin 7,3′‐di‐ O ‐glucoside were administered i.p. for 7 days (4 mg/kg b.w./day). The protective effect of these compounds over liver and kidneys of STZ–diabetic models was also evaluated by the determination of seric AST, ALT and urea levels. After 7 days of treatment, apigenin, chrysoeriol and genistein significantly lowered the blood glucose levels of diabetic animals; this effect was more pronounced (P < 0.01) in the oral glucose tolerance test. Glucose tolerance was also significantly improved in the rutin (P < 0.01) and in the genistein 7– O –glucoside (P < 0.05) treated groups. In addition, almost all the tested compounds effectively protected the liver and kidneys against STZ‐induced damage in rats. Copyright © 2010 John Wiley & Sons, Ltd.